PCA8574D-T - 8-Bit I2C I/O Expander 400kHz | NXP
Teilenummer: PCA8574D-T ✗ Abgekündigt| Menge | Stückpreis | Gesamt |
|---|---|---|
| 1 | $1.85 | $1,85 |
| 10 | $1.66 | $16,60 |
| 100 | $1.38 | $138,00 |
| 500 | $1.15 | $575,00 |
| 1.000 | $0.98 | $980,00 |
PCA8574D-T Übersicht
An I/O expander is a type of interface IC within the broader hierarchy of interface and connectivity semiconductors. It allows a microcontroller with limited GPIO pins to control additional digital inputs and outputs over just two bus lines, reducing pin count, board space, and wiring complexity. I/O expanders are common companions to MCUs such as those from NXP, STMicroelectronics, and Microchip in embedded systems.
Key features of the PCA8574D include an 8-bit quasi-bidirectional port with latched outputs, an open-drain interrupt (INT) output that alerts the host controller to remote input changes, and three hardware address pins (A0, A1, A2) that allow up to eight PCA8574 devices on the same I2C-bus. Combined with the PCA8574A variant (different fixed slave address), up to 16 devices can share one bus, supporting up to 128 I/Os, for example driving 128 LEDs.
Architecturally, the device integrates an 8-bit quasi-bidirectional I/O port, an I2C-bus slave interface with Fast-mode 400 kHz support, and power-on reset logic that sets all ports to a defined state at startup. The quasi-bidirectional structure means each pin can serve as input or output without a direction-control register, simplifying firmware.
Typical applications include keypad scanning and keyboard interfaces, LED and indicator driving, backplane status monitoring in industrial systems, and general-purpose GPIO expansion in automotive body electronics and consumer appliances.
Design consideration: quasi-bidirectional pins source a weak holding current when set high, so external loads must sink current to pull a pin low; check sink capability per the manufacturer datasheet before driving heavier loads.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet.
Drop-in-Alternativen für PCA8574D-T – gleiches Gehäuse, Pin-kompatibel. Bauteile mit anderem Gehäuse, die eine PCB-Überarbeitung erfordern, sind ausgeschlossen.
Varianten dieser Serie
Modelle derselben Serie, die drop-in-kompatibel sind mit PCA8574D-T (gleiche Bauform und Footprint) – abweichend in Function, Interrupt Output, Number of I/O, Output Type, RoHS Status.
Schnellvergleichstool – Wählen Sie Alternativbauteile für den Direktvergleich:
PCA8574AD,512
✅ Drop-In📋 Referenzalternative (nicht im Katalog)
PCA8574ATS
✅ Drop-In📋 Referenzalternative (nicht im Katalog)
PCF8574T/3
✅ Drop-In📋 Referenzalternative (nicht im Katalog)
PCF8574DW
✅ Drop-In📋 Referenzalternative (nicht im Katalog)
PCF8574AT/3,518
✅ Drop-In ⚠️ Spezifikationen ungeprüft✓ Auf Lager
$0.74 / Stück
Datenblatt ansehen →PCA8574D-T Technische Daten
| Funktion | Remote 8-bit I/O expander for I2C-bus with interrupt |
| Number of I/O | 8 (quasi-bidirectional) |
| Schnittstelle | I2C-bus (2-line: SCL, SDA) |
| I2C Bus Speed | 400 kHz (Fast-mode) |
| Gehäuse | SO16 (SOIC-16) |
| Montageart | Surface Mount |
| Address Pins | 3 (A0, A1, A2) |
| Max Devices per Bus (PCA8574/74A) | 16 (up to 128 I/Os) |
| Interrupt Output | Yes (open-drain INT) |
| Ausgangstyp | Quasi-bidirectional, latched |
| Packaging | Tape and Reel (-T suffix) |
| RoHS-Status | unknown |
| Lebenszyklusstatus | End of Life (per NXP product page) |
PCA8574D-T Pin-Konfiguration
| Pin 1 | A0 — Hardware address input 0 |
| Pin 2 | A1 — Hardware address input 1 |
| Pin 3 | A2 — Hardware address input 2 |
| Pin 4 | P0 — Quasi-bidirectional I/O port bit 0 |
| Pin 5 | P1 — Quasi-bidirectional I/O port bit 1 |
| Pin 6 | P2 — Quasi-bidirectional I/O port bit 2 |
| Pin 7 | P3 — Quasi-bidirectional I/O port bit 3 |
| Pin 8 | VSS — Ground supply |
| Pin 9 | P4 — Quasi-bidirectional I/O port bit 4 |
| Pin 10 | P5 — Quasi-bidirectional I/O port bit 5 |
| Pin 11 | P6 — Quasi-bidirectional I/O port bit 6 |
| Pin 12 | P7 — Quasi-bidirectional I/O port bit 7 |
| Pin 13 | INT — Interrupt output (open-drain, active low) |
| Pin 14 | SCL — I2C-bus serial clock input |
| Pin 15 | SDA — I2C-bus serial data input/output |
| Pin 16 | VDD — Supply voltage |
Typische Anwendungen
PCA8574D-T ist geeignet für 6 Anwendungs: Keypad and Keyboard Interface, LED Indicator Driving, Industrial Backplane Status Monitoring, Automotive Body Electronics GPIO Expansion, Consumer Appliance Control Panels, EOL Risk Mitigation and Legacy Design Rescue.
Keypad and Keyboard Interface
The PCA8574D-T suits keypad scanning because its 8 quasi-bidirectional pins handle row/column lines without a direction register, and its open-drain INT output flags the host MCU immediately on any key press. Over Fast-mode I2C at 400 kHz, row transitions and reads complete in microseconds, so even multi-matrix keypads respond without perceptible latency. Using the A0-A2 pins, several expanders can share one two-wire bus, extending a small MCU to large keypads with only SCL and SDA routed across the board, cutting MCU pin count and wiring harness complexity.
Empfohlen
LED Indicator Driving
NXP explicitly cites LED driving as a core use case: with up to 16 PCA8574/74A expanders on one I2C-bus, 128 LEDs can be controlled from a single two-wire interface. The latched quasi-bidirectional outputs hold their state between bus transactions, so LED patterns persist without host refresh, reducing firmware overhead and bus traffic. For status panels, backlights, and indicator clusters in industrial and consumer equipment, the expander converts a scarce MCU GPIO budget into a scalable, addressable LED matrix while the 400 kHz Fast-mode bus keeps pattern updates fast.
Empfohlen
Industrial Backplane Status Monitoring
In industrial backplanes and control cabinets, the PCA8574D-T consolidates discrete fault, door-interlock, and module-present signals onto the I2C-bus. Inputs on the quasi-bidirectional port generate an immediate interrupt via the open-drain INT pin, so the host controller responds to faults without polling every expander. The 3.3 V and 5 V logic compatibility typical of the family lets it bridge legacy 5 V backplane signaling and modern 3.3 V controllers. Address pins A0-A2 allow dense status aggregation across chassis slots while SCL/SDA routing stays minimal across the backplane.
Empfohlen
Automotive Body Electronics GPIO Expansion
Body control modules and comfort controllers frequently need more discrete I/O than the base MCU provides for switches, lamps, and relay monitors. The PCA8574D-T family's two-wire I2C expansion adds eight quasi-bidirectional pins per SO16 device at low cost, and multiple expanders scale to 128 I/Os on one bus. The interrupt output supports event-driven switch monitoring (door, seat, button), reducing current draw versus continuous polling - relevant to key-off battery drain budgets. Designers should qualify temperature range and AEC-grade requirements against NXP's automotive portfolio before production use.
Empfohlen
Consumer Appliance Control Panels
Washing machines, ovens, and HVAC controllers use the PCA8574D-T to merge button inputs and LED indicators onto one I2C-bus run to the front panel. The latched outputs keep indicator states stable even if the bus is briefly busy, and the INT pin wakes the MCU on user input, enabling low-power standby where the host sleeps between key presses. Address straps permit a single controller to serve panel I/O plus additional expander locations elsewhere in the appliance. The SO16 surface-mount package suits standard reflow assembly on cost-sensitive consumer PCBs.
Empfohlen
EOL Risk Mitigation and Legacy Design Rescue
With the PCA8574D now End of Life per NXP, this device's most practical application today is bridging legacy designs to available substitutes. NXP's own datasheet notes identify the PCA8574AD and the PCF8574 family as drop-in replacements, so production lines can be requalified without PCB rework. Engineers should inventory remaining PCA8574D-T stock against forecast demand, then validate the PCF8574T/3 or PCF8574DW on the same footprint, verifying supply-voltage range and interrupt polarity against the existing firmware before approving the substitution.
Empfohlen
Zusammenfassung der empfohlenen Produkte
Technische Referenzdaten für PCA8574D-T – Vergleich, Designhinweise und Compliance-Informationen.
Auswahlhilfe
Vergleich mit Alternativen
| Parameter | Dieses Produkt | PCA8574AD,512 | PCA8574ATS | PCF8574T/3 | PCF8574DW | PCF8574AT/3 |
|---|---|---|---|---|---|---|
| Package | SO16 | SO16 - same | SO16 - same | SO16 - same | SO16 (SO16W body) - same footprint | SO16 - same |
| Brand | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors |
| I/O Count | 8 quasi-bidirectional | 8 quasi-bidirectional | 8 quasi-bidirectional | 8 quasi-bidirectional | 8 quasi-bidirectional | 8 quasi-bidirectional |
| I2C Bus Speed | 400 kHz (Fast-mode) | 400 kHz (Fast-mode) | 400 kHz (Fast-mode) | 100 kHz (Standard-mode) | 100 kHz (Standard-mode) | 100 kHz (Standard-mode) |
| Interrupt Output | Yes (open-drain INT) | Yes (open-drain INT) | Yes (open-drain INT) | Yes (open-drain INT) | Yes (open-drain INT) | Yes (open-drain INT) |
| Fixed I2C Slave Address | PCA8574 address class | PCA8574A address class (alternate) | PCA8574 address class | PCF8574 address class | PCF8574 address class | PCF8574A address class (alternate) |
| Address Pins | 3 (A0, A1, A2) | 3 (A0, A1, A2) | 3 (A0, A1, A2) | 3 (A0, A1, A2) | 3 (A0, A1, A2) | 3 (A0, A1, A2) |
| EOL Replacement Path | Requires substitution | Documented drop-in for PCA8574D | Documented drop-in (family note) | Documented drop-in replacement | Complete replacement per FindIC | Drop-in with alternate address |
Wichtigste Unterscheidungsmerkmale
- Fast-mode 400 kHz I2C operation (vs. PCF8574T/3)
- Newer-generation architecture in the same SO16 footprint (vs. PCF8574DW)
- Bus scaling to 128 I/Os (vs. PCA8574AD,512)
- Open-drain interrupt for event-driven designs (vs. Generic GPIO-expanders without INT)
Designhinweise
In the SO16 footprint, place 100 nF ceramic decoupling directly across VDD (pin 16) and VSS (pin 8), with the trace loop minimized. SDA and INT are open-drain lines and require pull-up resistors - typical values are 1 kOhm to 10 kOhm depending on bus capacitance and target 400 kHz Fast-mode timing; verify rise-time compliance against I2C-bus specification limits for your bus capacitance.
Quasi-bidirectional pins are not push-pull outputs: when written high, the pin sources only a weak holding current, so driving loads that require pull-up strength (e.g., some optocoupler LEDs or NPN transistor bases) needs care. Loads should sink current to pull the pin low. Also remember the three address pins A0-A2 must be strapped to a defined logic level - floating address inputs produce unpredictable slave addressing on the I2C-bus.
Because the PCA8574D is End of Life, plan the power-budget validation of any substitution on the same footprint: PCF8574-class parts specify a low standby current, but exact limits differ between the PCA8574 and PCF8574 generations. Before approving a drop-in like PCF8574T/3, compare supply voltage range and per-pin sink current from the official NXP datasheets against your worst-case LED or relay-driver load currents.
On longer backplane or panel harness runs, bus capacitance grows quickly and can violate Fast-mode 400 kHz rise-time requirements. If INT or SDA lines exceed roughly 200-400 pF of effective capacitance (estimate from cable type and length), reduce the I2C clock to 100 kHz or add an active bus buffer. Keep INT routed away from switching regulator nodes to prevent false input-change interrupts.
Compliance-Informationen
Compliance details must be confirmed on the NXP PCA8574D product page (Environmental Quality section); no compliance data was present in the verified web data provided.
